Mobile flocculation and fracking water treatment system

ABSTRACT

A mobile flocculation and water treatment system includes at least one tank, preferably a series of adjoining tanks separated by weirs, and an adjacent pump house mounted on a mobile platform. At least one pump is mounted in the pump house. Fluid conduits run from the pumps to the tank. An overflow is mounted between the downstream tank and the pump house whereby fluid overflow from the tanks is directed into the pump house. The pump house provides a substantially water-tight reservoir zone to provide secondary containment. Water to be treated enters the upstream end of the tanks and is discharged from the downstream end.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/036,711 filed Sep. 25, 2013 which in turn claims priorityfrom Canadian Patent Application No. 2,791,441 filed Sep. 28, 2012, bothentitled Mobile Flocculation and Fracking Water Treatment System,entireties of which are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to the field of settling or flocculation tanksand in particular to an improved mobile flocculation and fracking watertreatment system wherein a series of settling or flocculation tankshaving a progression of weirs therebetween may be employed serially orindividually bypassed to allow cleaning of a particular tank and whereinoverflow is captured in at least a pump house mounted in-line with thetanks on an elongate skid or other mobile platform.

BACKGROUND OF THE INVENTION

As described by Kennedy et al in U.S. Pat. No. 8,110,115, water isessential to the oil and gas industry. In an oil or gas well, water isused to cool and lubricate the drillbit and to extract debris.Accordingly, drilling a well may require hundreds of thousands ofgallons of water. Water is also recovered as a byproduct of oil and gaswells as produced water.

Furthermore, the process of hydraulic fracturing uses a large amount ofwater. Hydraulic fracturing, or fracking (as it is commonly called andused herein), is a commonly used process to increase production andrecovery in an oil or gas well. In hydraulic fracturing, fluid isinjected at high pressure into a well to crack or fracture in the rockstructures possessing hydrocarbons. The fracture width is usuallymaintained through the use of a proppant such as sand, ceramic, or otherparticulates maintaining the fracture width allows hydrocarbons to flowto the surface of the well. In addition to fracturing the rock, wateralso serves as a transport medium for the proppant. Accordingly, thehydraulic fracturing process requires millions of gallons of water perwell. Often, a large percentage of the water used in hydraulicfracturing is recovered as flowback water.

Consequently, oil and gas companies must supply oil and gas wells withthe requisite amount of water, and must manage the flowback and producedwater recovered from the well. To accommodate the supply need, water istypically transported through temporary pipelines or trucked to the wellsite. However, water recovered from the well is unclean and filled withhydrocarbons, suspended solids, heavy metals, and bacteria. Therecovered water must therefore be filtered and cleaned before it can bereused in the fracking process or introduced into the environment. Forthis reason, the recovered water is typically trucked from the well siteto a filtering location, and then trucked from the filtering location toits next destination. The process of using trucks to transport the waterincreases the volume of traffic on roads and requires fossil fuels topower the trucks. Similarly, a company may construct a piping system topump the water through the piping system to and from a filteringlocation, but such a piping system is a considerable expense. As analternative to transporting the water by truck or constructing a pipingsystem, a filtering company may set up a facility at the well site tofilter the water, or bring in a large filtration system attached to atrailer to reuse the flowback water for the hydraulic fracturingprocess. However, this requires additional expense to set up a filteringfacility. Furthermore, once the hydraulic fracture process is complete,the recovered water must be transported to another location.

In the prior art applicant is also aware of the following United Statespatents and published patent applications which attempt to providemobile systems for water treatment:

U.S. Pat. No. 6,077,448 which issued Jun. 20, 2000, to Tran-Quok-Nam etal for An Oil/Grit Interceptor which discloses a multi-chambered tankproviding partial separation of pollutants contained in effluent. Withthe exception of effluent flow via a bypass in the event of tankoverloading, effluent drops into a first chamber and from the firstchamber passes to a second chamber. Trash and debris is collected in thefirst chamber and free petroleum based products are separated and heldin the second chamber. Effluent from the second chamber passes into athird chamber where sediment is separated.

U.S. Pat. No. 6,899,808 which issued May 31, 2005, to Ott for a SystemFor Processing Polluted Water discloses using inline first, second andthird containers where a pair of partitions separate the containers andwhere a corresponding pair of weirs are included in their respectivepartitions and are transversely offset from one another.

U.S. Pat. No. 7,578,930 which issued Aug. 25, 2009, to Williamson et alfor A Mobile Water Treatment System discloses the use of separation andfiltration components mounted on a trailer. The components are describedas removing particulates and filtering contaminants from effluent watersuch as storm water, waste water, or drain water. The trailer basedsystem is described as providing a mobile water treatment system whichcan be transported to a construction location or other storm water orwaste water site on a temporary basis and used to treat the water byremoving free and disbursed oils, capturing floatable debris, sedimentand settleable solids.

U.S. Pat. No. 8,110,115 which issued Feb. 7, 2012, to Kennedy et al forA Mobile Water Treatment discloses transporting dirty fluid in a storagecontainer on a motor vehicle between first and second locations whereinat the second location the fluid is filtered by a filtration system anddischarged. A pump is configured to on-load fluid into the storagecontainer and is also adapted to offload the fluid from the storagecontainer once the fluid has been filtered.

United States published patent application, publication no.2007/0246414, published on Oct. 25, 2007 in the application of Page etal for A Water Treatment And Apparatus Method describes the use ofcompartments for holding waste water and separator/recovery mechanisms,evaporation compartments, a condensation recovery system and a cleanwater holding compartment. In one disclosed embodiment, a platform suchas a skid supports a phase separation tank, an evaporation tank withcondenser, and a clean water recovery tank. Fluid transfer mechanismsinterconnect the tanks. The phase separation tank may provide threephase separation into solids, water and oil fraction. The fluid transferbetween the separation and evaporation tanks may pass through atransitional tank such as a floc tank.

United States patent application, publication no. 2008/0061003,published Mar. 13, 2008, in the application of Mueller for An ApparatusFor Recycling Of Oil Based Drilling Fluid Contaminated With Water AndWater Contaminated With Oil Based Drilling Fluid describes using anemulsion breaking tank, a water treatment tank, a filter press, andhydrocarbon filters. Mueller describes that there is a need for askid-mounted apparatus to effectively break emulsions on an off shorerig thereby reducing the need to transport slop water on shore. Muellerdescribes, in one embodiment, the use of two modules wherein one moduleseparates the bulk part of the water fraction from oil based/syntheticbased drilling mud, from where the extracted water is pumped to thesecond module where it is treated with a flocculent toeliminate/minimize hydrocarbon, organic and heavy metal contamination.The treatment sludge containing the contaminant loaded flocculent isdirected to a filter press for dewatering and solidification fortransport and disposal. The cleaned water phase is then pumped over afurther filter and discharged.

United States patent application, publication no. 2009/0178978,published Jul. 16, 2009, in the application of Beebe et al for DrillingFluid Treatment Systems describes the use of at least one holding tankmounted on a base for holding well fluid to be treated, a centrifuge forcentrifuging a mixture of well fluid and solids from the at least oneholding tank to produce reusable fluid, and a mixing tank for mixing anaqueous solution for introduction to the well fluid held in the at leastone holding tank. The aqueous solution includes flocculent andcoagulant.

Beebe et al describe that U.S. Pat. No. 4,536,286 discloses atransportable waste treatment which is completely mobile and capable oftreating high mud volumes. This system is self-contained having chemicalstorage, chemical pumps, sludge pumps, water pumps, laboratory,centrifuge, conveyors, etc., and has weight, height and width suitablefor highway travel A skid incorporates three settling tanks and twochemical tanks for flocculation. Waste liquids containing solids enter afirst settling tank and are mixed with flocculation chemicals. Solidssettle to the tapered bottom of the tank for collection by a suctionlocated at the apex of the tank bottom. Partially clarified liquid fromthe first settling tank overflows a weir to the next adjacent settlingtank and similarly for the second to the third settling tank.

SUMMARY OF THE INVENTION

In summary, the mobile flocculation and water treatment system andmethod may be characterized in one aspect as including at least one tankand an adjacent pump house, all mounted on a single mobile platform suchas a skid.

The tank is preferably a series of tanks or compartments having an inletand an outlet at substantially opposite ends thereof. The pump house maysubstantially adjoin the downstream tank, compartment or end of theseries of tanks. At least one pump is mounted in the pump house. Fluidconduits run from the pumps to the tank provide for pumping fluid to atleast the inlet, and advantageously both to the inlet and from theoutlet.

An overflow conduit is mounted in fluid communication between thedownstream tank, compartment of downstream end of the series of tanksand the pump house whereby fluid overflow from the tanks is directedthrough the overflow conduit and into the pump house. The pump house hasan upper zone atop a reservoir zone. The pumps are mounted in thereservoir zone. The reservoir zone is substantially water-tight toprovide secondary containment of a secondary containment fluid volume ofthe fluid.

The tanks are preferably an in-line plurality of tanks separated by acorresponding plurality of weirs, wherein each weir is of the higherelevation than a next most adjacent downstream weir. In particular theplurality of tanks may include three tanks, namely an upstream tank, amid-stream tank and a downstream tank. The flow inlet directs theincoming fluid into the upstream tank. Thus the plurality of weirs mayinclude a first weir between the upstream tank and the midstream tank,and a second weir between the midstream tank and the downstream tank. Acommon downstream wall separates the downstream tank and the pump house.The overflow conduit is in the common wall.

The elevation of the overflow conduit is great than the elevation of thefirst weir. The elevation of the second weir is less than the elevationof the first weir. The upper edges of the tanks have an elevation whichis no less than the elevation of the overflow conduit.

Advantageously the pump house is in-line with the plurality of tanks andincludes a water-tight, low-rise wall surrounding and sealed so as to bewatertight with the floor of the pump house to thereby form thereservoir zone of the pump house. The pump house may further includes atleast one filter cooperating with the pumps. An access door may beprovided above the low rise wall of the reservoir zone. In oneembodiment the low-rise wall stands approximately four inches high.

In a preferred embodiment a fluid diverting flume extends longitudinallyalong and over at least the upstream and midstream tanks. The flume hasan upstream end cooperating with, to receive the fluid from, the inlet.The flume has selectively biasable doors, biasable between open andclosed positions, along the flume for selectively directing the fluidflowing along the flume into either the upstream tank or the midstreamtank. A fluid bypass may in addition to, or alternatively to cooperatewith the flume to bypass the fluid around one or more of the pluralityof tanks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is, in side elevation view, the fluid tank and pump house restingon a skid.

FIG. 2 is, in plan view, a diagramatic illustration of the tank and pumphouse of FIG. 1.

FIG. 2a is an enlarged side elevation view of one pumping system withinthe pump house of FIG. 2.

FIG. 3 is, in side perspective view, the skid mounted tank and pumphouse of FIG. 1.

FIG. 4a is, in end elevation view, the end of the tank of FIG. 3.

FIG. 4b is, in end view, the end of the tank opposite to the end of FIG.4 a.

FIG. 5 is, in partially cut away plan view, the tank end of FIG. 4 b.

FIG. 6 is, in partially cut away top perspective view, a view from thetank end of FIG. 5 along the tank of FIG. 3, with the water troughcovers in the open position.

FIG. 7 is a top perspective view showing the water trough covers intheir closed position.

FIG. 8 is, in perspective view, the inside of the pump house of FIG. 2looking from the doorway end of pump house at the filter units andspillway.

FIG. 9 is, in perspective view, an enlarged view of the spillway of FIG.8.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In one embodiment of the mobile flocculation and water treatment systemaccording to the present invention, a tank 10 and an adjacent pump house12 are mounted on a portable platform such as skid 14. In oneadvantageous use of the present system, which is not intended to belimiting, in the oil and gas industry so called “sweet” water isrecycled for use in so called “fracking” or hydraulic fracturingoperations which would benefit from the on-site treatment andreclamation of fracturing fluids such as by the settling clarificationof treated fluids. Such fluids may be treated for example in aflocculation process to form a sludge which settles out in the tankleaving clarified fluid to be then further filtered before discharge forrecycling.

In one embodiment such as seen in FIG. 1, which is not intended to belimiting, the combined length of tank 10 and pump house 12 resting onskid 14 corresponds to the length of a conventional trailer, for example56 feet. Advantageously, as illustrated, tank 10 and pump house 12 aremounted in-line on skid 14 so as to present a substantially uniformwidth, for example a width of 10 feet, again for convenient and legalloading on a conventional trailer. Within the 56 foot combined length,in one embodiment, tank 10 is approximately 30 feet long and includes aspaced apart pair of weirs, respectively weirs 16 a and 16 b formingin-line serial compartments 10 a, 10 b and 10 c.

Contaminated water is pumped into compartment 10 a through an upstreaminlet so as to fill compartment 10 a behind weir 16 a. Weir 16 a has aheight h1 which is greater than the height h2 of weir 16 b. In oneembodiment height h1 may be substantially 54 inches, and height h2 maybe substantially 51 inches. Compartment 10 b is defined between weirs 16a and 16 b. Compartment 10 b is the next adjacent downstream compartmentto compartment 10 a. Compartment 10 c is the next adjacent downstreamcompartment to compartment 10 b and is defined between weir 16 b and thedownstream end wall 20 of tank 10.

As contaminated fluid such as return fluid from fracking operations ispumped into compartment 10 a, once it reaches a level equivalent toheight h1, it over flows weir 16 a into compartment 10 b. Similarly,compartment 10 c is gravity fed as the level of the fluid in compartment10 b exceeds height h2. If flocculating chemicals are added to the fluidin one of the compartments, the resulting solids are allowed to settleout to form a sludge in the bottom of the compartment. Other solids arealso allowed to settle out within the compartments so that the mostclarified fluid is the fluid in the downstream most compartment 10 c.

Pump house 12 adjacent end wall 20 may share a common end wall 20 andmay have a length of for example 23 feet. Pump house 12 may house aduplex filter arrangement having a six inch so-called mission-stylepump.

Contaminated water may be pumped into tank 10 through for example pipeshaving a diameter in the range of 3-4 inches. Inlet 18S isadvantageously a pair of inlets that direct incoming water into theupstream end of a trough 22, although this is not intended to belimiting as other fluid conduits including open and closed-top channelswould work; and herein collectively also referred to as a flume. Anupstream diffuser, for example a six inch conventional diffuser (notshown), is employed to decrease the velocity of the water entering intotrough or flume 22 and as well act to commence the settling out of sandor other solids from the incoming contaminated water. One or more suchdiffusers may be housed within a gas box 24. Gases which are entrappedwithin the inflow of contaminated water are allowed to escape so as totravel up a vent stack, for example, the eight inch diameter vent stack26 illustrated. Incoming water leaving gas box 24 drops into trough orflume 22. Trough or flume 22 directs the incoming water into compartment10 a which effectively provides the first of three in-line compartmentsor tanks within tank 10. Compartment 10 a may advantageously havedimensions of approximately 10 feet in length by 10 feet in width, whichdimensions are not intended to be limiting. Again, solids in theincoming water are allowed to drop out and settle within compartment 10a.

Advantageously, approximately one foot upstream from weir 16 a, that is,upstream relative to downstream flow direction A, an oil-phase weir (notshown) may be mounted so as to extend downwardly past the elevation h1of weir 16 a to thereby trap and hold any oils or otherlighter-than-water fluids or solids floating in compartment 10 a. Thusthe lighter than water fluids or floating solids are inhibited fromentering into compartment 10 b.

In the illustrated embodiment compartment 10 b is also a 10 foot by 10foot sized compartment, although again the dimensions are not intendedto be limiting. Solids that have not settled out from the fluid incompartment 10 a are allowed to settle out in compartment 10 b. Again,an oil-phase weir is mounted over and upstream of weir 16 b to hold backany lighter-than-water fluids and floating solids that may have carriedover weir 16 a.

Trough or flume 22 may, as illustrated, extend over and along thecomplete length of both compartments 10 a and 10 b. A steel plate 22 amounts into trough or flume 22, for example approximately midway alongtrough or flume 22. Steel plate 22 a may be mounted into trough or flume22 for example by a sliding mount between guides mounted to the walls oftrough or flume 22. Thus gate 22 a is removable. With gate 22 ainstalled into trough or flume 22, water flowing into trough or flume 22from gas house 24 is contained behind gate 22 a which blocks flowfurther downstream along through or flume 22. Thus the flow flows onlyinto compartment 10 a.

The outflow from trough or flume 22 into compartment 10 a is controlledby removable gates 22 b removably mounted as by a snug sliding fit intothe side walls of trough or flume 22. Thus gates 22 b are removed fromtrough or flume 22 when it is desired to fill compartment 10 a. When itis desired to isolate compartment 10 a for cleaning, gates 22 b areremounted into trough or flume 22 and gate 22 a is removed so that theincoming flow of contaminated water flows along the length of trough orflume 22 downstream so as to be above compartment 10 b. In order to thusbypass compartment 10 a gates 22 c are removed from the downstream endof trough or flume 22 thereby allowing the incoming contaminated waterto fill compartment 10 b.

A further trough 28 may similarly be employed to bypass compartment 10 bwhen it is desired to empty compartment 10 b for cleaning.

The clarified water in compartment 10 c is pumped and filtered fordischarge. Suction lines having for example 2-4 inch diameters aremounted in fluid communication with compartment 10 c. The upstream endsof the suction lines 30 are maintained off the bottom of tank 10 by theuse of adjustable skimmers (not shown). A gauge (not shown) such as afloat rod and ball arrangement, allows the fluid level in compartment 10c to be monitored from inside pump house 12. At least two float switches(not shown) and preferably three float switches in compartment 10 cprovide for the automatic activation and deactivation of pumps 32mounted in pump house 12. In a preferred embodiment, the third floatswitch may be provided to detect a high fluid level in the compartment,for example at fluid levels at or exceeding approximately 69 incheselevation.

Preferably an overflow conduit such as spillway 34 is mounted forexample in end wall 20 at a height h3 of 69 inches. Spillway 34 allowsthe water to spill over into a secondary containment in case ofinadvertent overflow thereby minimizing the impact of spills. Thesecondary containment is provided by secondary containment reservoirs.In a preferred embodiment a water-tight lower reservoir zone of pumphouse 12 serves as one secondary containment reservoir. In thatpreferred embodiment, the lower reservoir zone includes a reservoircontained by a low-rise wall and the floor 12 b to provide a sealedvessel for example allowing for the containment of 2000 litres ofspilled water. Pump house 12 may include at least one door 12 a. Thelow-rise wall is below the door and may for example be four inches inheight to provide the lower water tight reservoir zone of pump house 12which provides the secondary containment reservoir.

An additional secondary containment reservoir may be provided around thefilter unit 36 which advantageously provides yet a further 2000 litrecontainment vessel.

Inside pump house 12 a suction line 30 runs from the skimmers to adiesel powered mission style pump 32. A shut off valve 30 a on line 30isolates the tank 10. Another valve (not shown) that leads to outside oftank 10 provides for out of pumping external tanks or trucks. A furthertwo inch suction valve on line 30 allows pumping out of the reservoirsany water that may enter the secondary reservoirs. The water is pumpedthrough the pumps 32 into a duplex bag filter unit 36. The water isfiltered as appropriate for the application. Because filter unit 36 is aduplex system the filters may be changed on the fly by personneloperating the tank. A by-pass valve is provided (not shown), located inthe piping behind the filter unit, so that water may be pumped withoutfiltration. Once the water has been filtered it may be reintroduced tothe frac water compartment(s) of tank 10, using two-six inch outlets onthe pump house.

The pumps 32 may be equipped with automatic start and stop. Thus tank 10may always be kept at a safe level to eliminate spills. In case ofemergency the pump 32 will start up and pump water that may enter tank10 without the operator knowing. The pumps 32 may also be equipped withan automatic RODA-DEACO valve that will shut the motor down in the eventthat flammable gas is introduced to the intake. The intake and exhaustfor the motor are advantageously on the outside of the pump house, forexample, at twenty-three feet from the open top on tank 10 as may berequired by regulations.

Inside the pump house there may be a beacon light that will come on whenthe high level alarm float is triggered. There may also be the othervisual and audible warning devices may be provided on the outside of thepump house to let the operator know if there is a problem. An exhaustfan (not shown) may be provided to exhaust any hazardous gases that mayenter the pump house.

Moreover, in interpreting both the specification and the claims, allterms should be interpreted in the broadest possible manner consistentwith the context. In particular, the terms “comprises” and “comprising”should be interpreted as referring to elements, components, or steps ina non-exclusive manner, indicating that the referenced elements,components, or steps may be present, or utilized, or combined with otherelements, components, or steps that are not expressly referenced.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

What is claimed is:
 1. A method for providing mobile flocculation andfluid treatment comprising the steps of: a) providing at least one tankhaving an inlet and an outlet at substantially opposite ends thereof, b)providing a pump house substantially adjoining said at least one tank,at least one pump mounted in said pump house, c) an overflow conduit influid communication between said at least one tank and said pump house,d) providing a mobile platform and mounting said at least one tank andsaid pump house on said mobile platform, e) pumping fluid for treatmentinto and through said inlet so as to flow into said at least one tank,f) after a dwell and settling-out time of said fluid within said atleast one tank whereby solids settle out of said flow in said at leastone tank, said flow exiting from said outlet, and g) in the event offluid overflow from said at least one tank, said fluid overflow beingdirected through said overflow conduit into said pump house forcontainment within secondary containment reservoirs within the pumphouse, wherein secondary containment reservoirs include a firstsecondary containment reservoir defined by a low-rise wall extendingcontiguously around and sealed to a floor of said pump house, and asecondary containment reservoir within said first secondary containmentreservoir.
 2. The method of claim 1 wherein said step of providing saidat least one tank includes providing an in-line plurality of tanksseparated by a corresponding plurality of weirs, wherein each weir ofsaid plurality of weirs is of the higher elevation than a next mostadjacent downstream weir of said plurality of weirs.
 3. The method ofclaim 2 wherein said plurality of tanks includes three tanks, said threetanks comprising an upstream tank, a midstream tank and a downstreamtank, wherein said inlet directs said fluid into said upstream tank. 4.The method of claim 3 wherein said plurality of weirs includes a firstweir between said upstream tank and said midstream tank, and a secondweir between said midstream tank and said downstream tank, and wherein acommon wall separates said downstream tank and said pump house, andwherein said overflow conduit is in said common wall, and wherein anelevation of said overflow conduit is greater than an elevation of saidfirst weir, and an elevation of said second weir is less than saidelevation of said first weir, and wherein said plurality of tanks haveupper edges having an upper edge elevation which is no less than saidelevation of said overflow conduit.
 5. The method of claim 4 whereinsaid pump house is in-line with said plurality of tanks, and whereinsaid pump house includes an access door, and wherein said low-rise wallis below said access door.
 6. The method of claim 5 wherein said pumphouse further includes at least one filter cooperating with said atleast one pump.
 7. The method of claim 3 wherein a fluid diverting flumeextends longitudinally along and over at least said upstream andmidstream tanks, and wherein said flume has an upstream end cooperatingwith, to receive said fluid from, said inlet, and wherein said flume hasselectively biasable doors, biasable between open and closed positions,along said flume for selectively directing said fluid flowing along saidflume into either said upstream tank or said midstream tank.
 8. Themethod of claim 7 further comprising a fluid bypass cooperating withsaid flume to bypass said fluid around one or more of said plurality oftanks.
 9. The method of claim 1 wherein said at least one tank and saidpump house are mounted in-line on a mobile platform.
 10. The method ofclaim 9 wherein said mobile platform is a skid.